308 THE PRACTICAL APPLICATION OF ECOLOGY 



Each of these sub-species develops into the phases already 

 alluded to. The very wide range of this species, as a whole, 

 refers more especially to the limits to which odd specimens from 

 swarms extend and transformation into the phase solitaria takes 

 place. In the palaearctic region its breeding grounds, as at present 

 known, are centred more especially in middle Asia among the 

 vast reed-beds located in the vicinity of the Caspian and Aral 

 Seas and of Lake Balkhash. In Western Europe permanent 

 breeding grounds (swarm centres) no longer exist, most probably 

 owing to the spread of cultivation and its effects upon the original 

 ecological conditions of such areas. The Central Russian Locust 

 has its breeding grounds in small areas of sandy soil with sparse 

 vegetation. The African Locust has a most important breeding 

 ground in reedy areas in the Middle Niger region of the French 

 Sudan, from which all the recent invasions of that insect took 

 origin. The breeding grounds of the Madagascar Locust in 

 South Madagascar are in arid country with light soil and liable 

 to be flooded during rains. The Oriental Locust has diverse 

 types of breeding grounds : in China they resemble those of 

 the African Locust, while in Borneo, etc., they appear to be in 

 areas of humid tropical forest. It needs to be stressed that 

 comparatively little is yet known as to these breeding grounds 

 of each sub-species : their discovery and study forms one of the 

 most important aspects of the locust problem. 



2. The Desert Locust (Schistocerca gregaria Forsk). 



Phasis gregaria = gregaria Forsk. 



Phasis solitaria = flaviventris Burm. 

 The Desert Locust has likewise a very wide distribution in 

 the Old World. It covers nearly the whole of Africa, besides 

 Arabia, Palestine, Syria, Persia and Western India. It is 

 definitely connected with dry desert and semi-desert conditions 

 and, ecologically, it differs markedly from the preceding species. 

 In point of destructiveness it deserves first place among locusts 

 of the Old World, and records of its ravages extend far back 

 into history, including Biblical times. A very extensive literature, 

 which is rapidly growing, exists with reference to this species, and 

 in particular the memoirs by Bodenheimer (1929) and by Ballard 



